Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries the full burden. It states what is computed but omits return format, edge cases, and any behavioral traits. For a pure calculation tool with no annotations, this is a significant gap.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single concise sentence, front-loaded with the core operation and free of filler. It is appropriately sized for a simple tool, though it could be slightly more informative without becoming verbose.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema and a nested input object, the description should at least state the return format (e.g., a lat/lon coordinate) and clarify the input structure. It does neither, leaving an agent to infer from parameter names alone. This is insufficient for confident invocation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, and the nested payload contains four numeric fields (lat1, lon1, lat2, lon2) with no descriptions. The description's phrase 'two lat/lon points' adds some conceptual mapping but does not clarify order, coordinate system, or format beyond the parameter names themselves.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific computation: 'great-circle midpoint between two lat/lon points.' This distinguishes it from siblings like geo_distance and geo_bearing, which compute distance and bearing respectively. However, it does not explicitly name those alternatives, so sibling differentiation is implicit.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

No guidance on when to use this tool versus other geo_* siblings. No context, prerequisites, or exclusions are provided. The description simply states the operation without any usage cues.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.